<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>My Canvas</title>
    <style>
        .ui {
            position: absolute;
            left: 50%;
            bottom: 5%;
            width: 300px;
            margin-left: -150px;
        }

        .input {
            width: 100%;
            height: 50px;
            background: none;
            font-size: 24px;
            font-weight: bold;
            color: #000;
            text-align: center;
            border: none;
            border-bottom: 2px solid black;
        }

        .input:focus {
            outline: none;
            border: none;
            border-bottom: 2px solid black;
        }

        .return {
            display: none;
            position: absolute;
            top: 20px;
            right: 0;
            padding: 3px 2px 0 2px;
            font-size: 10px;
            line-height: 10px;
            color: #000;
            border: 1px solid #000;
        }

        .ui_enter .return {
            display: block;
        }
    </style>
</head>
<body>
<canvas class="canvas"></canvas>

<div class="ui">
    <input class="input" type="text"/>
    <span class="return">↵</span>
</div>

<script src="js/particle_system.js"></script>
<script src="js/demo1.js"></script>
</body>
</html>